The overall objective of this program is to develop optimized framework and marginal design of porcelain-fused-to-metal restorations. Such design will be based on stress analyses, mechanical tests, thermal compatibility measurements and fractographic examination of representative metal-ceramic systems. The specific aims are as follows: 1. Finite element stress analysis will be performed on proposed metal framework and porcelain design configurations. 2. Single cycle and multicycle stresses will be applied to porcelain-metal crowns to the point of porcelain fracture using both static loads in an Instron testing machine and dynamic loads in a laboratory stress cycling apparatus. 3. Fractographic examination of failed specimens will be accomplished employing: a) energy dispersive analysis of X-rays, b) SEM analysis, c) electron spectroscopy for chemical analysis, and d) metallographic-topographic observations. 4. A thermal shock test will be employed to investigate the potential correlation of thermal expansion/contraction behavior with the incidence of stress-induced crazing in porcelain. 5. Localized marginal distortion or generalized coping distortion of single unit simulated clinical crowns will be measured and possible correlations of these distortions with metal-porcelain thermal contraction differences will be identified. 6. The sag (creep) potential of alloys will be determined for cast metal strips using a bending beam viscometer. 7. The potential clinical relevance of sag will be investigated through the measurement of distortion of fixed partial prostheses with as-cast and post-soldered frameworks.